1. Field of the Invention
The present invention relates to a current sensor that measures the magnitude of a current. More particularly, the present invention relates to a current sensor in which a reduction in the measurement accuracy due to disturbance magnetic fields is prevented.
2. Description of the Related Art
In the field of a motor driving technique or the like used in electric cars or hybrid cars, a comparatively large current is handled. Thus, for such an application, there has been a demand for a current sensor that can measure a large current in a noncontact manner. As such a current sensor, a current sensor using a scheme in which a change in a magnetic field generated by a measurement target current is detected using magnetic sensors has been put to practical use. Regarding the current sensor using magnetic sensors, a reduction in the measurement accuracy due to the influences of disturbance magnetic fields is a problem. Thus, a scheme for preventing a reduction in the measurement accuracy due to the influences of disturbance magnetic fields has been proposed.
As the scheme for preventing a reduction in the measurement accuracy due to the influences of disturbance magnetic fields, for example, a scheme has been proposed, in which the influences of disturbance magnetic fields are made to cancel each other out by providing magneto impedance (MI) elements in opposite directions for a magnetic field generated by a detection target current (see Japanese Unexamined Patent Application Publication No. 2001-305163).
As the magnetic sensors used in the above-described current sensor, in addition to the MI elements, giant magneto resistance (GMR) elements, Hall elements, or the like are used. In the case where GMR elements or the like are used in a current sensor, even when the technique described in Japanese Unexamined Patent Application Publication No. 2001-305163 is applied, marked reduction of the influences of disturbance magnetic fields may be impossible.